The molecular structure of amyloid plaque, which is characteristic of diseases such as scrapie and type II diabetes, is unknown, due to the fact that amyloid is noncrystalline and insoluble. This proposal concerns the development of a general method for the determination of amyloid structure. Stable isotope (13C, 2H, 15N) labels are specifically incorporated into amyloid peptides and proteins by chemical synthesis. Subsequently, interatomic distances are measured by solid-state NMR, either by the rotational resonance or by the RF-driven recoupling technique. These distances are used as constraints for a simulated annealing energy optimization which will provide a structure for the protein aggregate. Partial structures of fragments of the amyloid proteins of AD and type II diabetes have been determined using this approach and significant structural differences between the two amyloids have been found. These results have prompted a reexamination of the widely accepted model for amyloid structure. This proposal concerns the development of new chemical, spectroscopic, and computational methods. This new technology will be applied to further study of the amyloid protein of type II diabetes (IAPP) and to the amyloid protein, or infectious prion, of scrapie (PrP). A knowledge of the structure of amyloid plaque will allow the design of molecules which bind to these structures. These molecules could be used to image brain amyloid and thus may have utility as diagnostics of prion diseases and/or type II diabetes.